[0001] The present invention relates to control of moisture inside a packaged electronic
device and relates particularly to highly moisture-sensitive electronic device elements
having multiple highly moisture-sensitive electronic devices and methods for their
fabrication to prevent premature device failure or premature degradation of device
performance.
[0002] In manufacturing, electronic devices are typically produced by fabricating large
substrates containing multiple electronic devices. These substrates are typically
selected from the group consisting of glass, plastic, metal, ceramic, silicon and
other semiconductor materials, or combinations of these materials. The substrates
may be rigid or flexible and may be handled as individual units or continuous rolls.
The primary reason for fabricating multiple electronic devices on large individual
substrates or a continuous roll substrate is to reduce manufacturing cost by decreasing
handling, increasing throughput, and increasing yield. In the micro-electronics industry
silicon wafer processing has increased from 2 inch wafers to 12 inch wafers resulting
in significant cost reductions. In the liquid crystal display (LCD) industry glass
substrate processing has increased from 300 mm x 400 mm substrates to over 600 mm
x 700 mm substrates with the same result. In manufacturing of highly moisture-sensitive
electronic devices, such as organic light-emitting devices (OLED), polymer light-emitting
devices, charge-coupled device (CCD) sensors, and micro-electro-mechanical sensors
(MEMS), the same economies of scale are achieved by fabricating large individual substrates
or a continuous roll substrate with multiple highly moisture-sensitive electronic
devices. FIG. 1A shows an unencapsulated highly moisture-sensitive electronic device
element 14 containing multiple highly moisture-sensitive electronic devices 12 on
an individual substrate 10, and FIG. 1B is a schematic sectional view of the highly
moisture-sensitive electronic device element 14 taken along section line 1B-1B of
FIG. 1A. Fabricating large individual substrates or a continuous roll substrate with
multiple highly moisture-sensitive electronic devices, however, introduces a problem
that is not important for less moisture-sensitive electronic devices in that highly
moisture-sensitive devices must be protected from even short term exposure to moisture
during fabrication.
[0003] Typical electronic devices require humidity levels in a range of about 2500 to below
5000 parts per million (ppm) to prevent premature degradation of device performance
within a specified operating and/or storage life of the device. Control of the environment
to this range of humidity levels within a packaged device is typically achieved by
encapsulating the device or by sealing the device and a desiccant within a cover.
Desiccants such as, for example, molecular sieve materials, silica gel materials,
and materials commonly referred to as Drierite materials, are used to maintain the
humidity level within the above range. Short term exposure to humidity levels greater
than 2500 ppm during the fabrication and encapsulation of these types of electronic
devices typically does not cause measurable degradation of device performance. For
this reason, encapsulation of these types of electronic devices is done after the
electronic devices are separated from the initial substrate.
[0004] In the manufacture of liquid crystal displays the electronics and the liquid crystal
materials are not highly moisture-sensitive; therefore, the process for encapsulating
the electronics and the liquid crystal materials does not require protection from
ambient moisture during fabrication. FIG. 2A shows a typical multiple LCD element
28 before separation into single LCD devices, and FIG. 2B is a schematic sectional
view of the multiple LCD element 28 taken along section line 2B-2B of FIG. 2A. In
LCD manufacturing the LCD back-plane 22 and the LCD front-plane 24 contain multiple
LCD devices. The LCD back-plane 22 and the LCD front-plane 24 are bonded together
with a sealing material 20 that surrounds each LCD device except for a gap in the
sealing material 20. After fabrication of the multiple LCD element 28 the LCD devices
are separated and filled with liquid crystal material. After filling the LCD devices,
the gap in the sealing material 20 is sealed with a gap sealing material to retain
the liquid crystal material and to protect the LCD back-plane electronics 26 and the
liquid crystal material from moisture. Because LCD devices are not highly moisture-sensitive,
the separation process of the multiple LCD element is typically performed in an ambient
air environment with no measurable degradation of the LCD devices.
[0005] Particular highly moisture-sensitive electronic devices, for example, organic light-emitting
devices (OLED) or panels, polymer light-emitting devices, charge-coupled device (CCD)
sensors, and micro-electro-mechanical sensors (MEMS) require humidity control to levels
below about 1000 ppm and some require humidity control below even 100 ppm. Such low
levels are not achievable with desiccants of silica gel materials and of Drierite
materials. Molecular sieve materials can achieve humidity levels below 1000 ppm within
an enclosure if dried at a relatively high temperature. However, molecular sieve materials
have a relatively low moisture capacity at humidity levels at or below 1000 ppm, and
the minimum achievable humidity level of molecular sieve materials is a function of
temperature within an enclosure: moisture absorbed, for example, at room temperature,
can be released into the enclosure or package during temperature cycling to higher
temperature, such, as, for example, to a temperature of 100°C. Desiccants used within
such packaged devices include powders of metal oxides, alkaline earth metal oxides,
sulfates, metal halides, or perchlorates, that is, materials having desirably relatively
low values of equilibrium minimum humidity and high moisture capacity. However, such
materials often chemically absorb moisture relatively slowly compared to the above-mentioned
molecular sieve, silica gel, or Drierite materials. Such relatively slow reaction
with water vapor leads to a measurable degree of device degradation of performance
following the sealing of the desiccant inside a device cover due to, for example,
moisture absorbed on the inside of a device, moisture vapor present within the sealed
device, and moisture permeating through the seal between the device and the cover
from the outside ambient. In addition, highly moisture-sensitive electronic devices
typically cannot be exposed to moisture levels greater than 1000 ppm even during fabrication
and encapsulation, requiring control of the moisture levels until the devices are
completely encapsulated. For these reasons, control of the moisture level during fabrication
and encapsulation is required to prevent degradation of performance.
[0006] To reduce the quantity of moisture absorbed on the inside of a device or present
within the sealed device, highly moisture-sensitive devices, such as organic light-emitting
devices (OLED) or panels, polymer light-emitting devices, charge-coupled device (CCD)
sensors, and micro-electro-mechanical sensors (MEMS), are often sealed within a low
humidity environment, such as a drybox at humidity levels less than 1000 ppm moisture.
To ensure low levels of moisture within the sealed device, these highly moisture-sensitive
devices are completely sealed within the low humidity environment prior to any additional
processing steps, such as bonding of interconnects and module assembly. To achieve
this low humidity sealing, highly moisture-sensitive devices, such as charge-coupled
device (CCD) sensors and micro-electro-mechanical sensors (MEMS), are typically sealed
individually as single elements with separate cover elements after separation from
a multiple element substrate or wafer. Other devices, such as organic light-emitting
devices (OLED), are sealed as multiple devices on a single element; however, in present
manufacturing methods individual cover elements of metal or glass are used to seal
each device prior to separation. FIG. 3A shows a typical multiple OLED element 34
containing multiple OLED devices 32 on an individual substrate 10, encapsulated with
individual encapsulation enclosures 30 and sealing material 20, and FIG. 3B is a schematic
sectional view of the multiple OLED element 34 taken along section line 3B-3B of FIG.
3A. Both of the present methods of sealing highly moisture-sensitive devices require
significant levels of handling to assemble individual cover elements to either individual
device elements or multiple device elements within a low moisture environment.
[0007] To reduce the handling of individual cover elements for encapsulation of multiple
highly moisture-sensitive device elements within a low moisture environment, a modification
of the LCD sealing method can be envisioned where the sealing material between the
substrate and the encapsulation enclosure has no gaps prior to bonding. FIG. 4A shows
a highly moisture-sensitive electronic device element 14 comprising a substrate 10
containing multiple highly moisture-sensitive electronic devices 12, a single encapsulation
enclosure 30 encapsulating all of the highly moisture-sensitive electronic devices
12, and sealing material 20. The problem with this technique is shown schematically
in FIG. 4A where the sealing material 20 has been damaged by the high gas pressure
inside each seal region produced when the substrate 10 and the encapsulation enclosure
30 are moved to their predetermined spacing after both the substrate and the encapsulation
enclosure have contacted the sealing material. This damage typically appears as narrow
seal widths or even gaps in the seal, decreasing or eliminating protection of the
highly moisture-sensitive electronic devices. FIG. 4B is a schematic sectional view
of the highly moisture-sensitive electronic device element 14 taken along section
lines 4B-4B of FIG. 4A. It would, therefore, be desirable to have highly moisture-sensitive
electronic device elements and a method for fabricating highly moisture-sensitive
electronic device elements that does not damage the seals that are required to protect
the highly moisture-sensitive electronic devices from moisture during fabrication
and encapsulation.
[0008] Numerous publications describe methods and/or materials for controlling humidity
levels within enclosed or encapsulated electronic devices. For example, Kawami and
others, European Patent Application EP 0 776 147 A1 disclose an organic EL element
enclosed in an airtight container which contains a drying substance comprised of a
solid compound for chemically absorbing moisture. The drying substance is spaced from
the organic EL element, and the drying substance is consolidated in a predetermined
shape by vacuum vapor deposition, sputtering, or spin-coating. Kawami and others teach
the use of the following desiccants: alkali metal oxides, alkali earth metal oxides,
sulfates, metal halides, and perchlorates. Kawami and others, however, do not teach
a multiple EL device element with multiple airtight containers nor a method for fabricating
a multiple EL device element with multiple airtight containers. The handling and sealing
problems and solutions of a multiple EL device element, such as methods to prevent
damage to the seal due to high gas pressure inside the seal region during encapsulation,
are not discussed nor taught by Kawami and others.
[0009] Shores, US-A-5,304,419, discloses a moisture and particle getter for enclosures which
enclose an electronic device. A portion of an inner surface of the enclosure is coated
with a pressure sensitive adhesive containing a solid desiccant.
[0010] Shores, US-A-5,401,536, describes a method of providing a moisture-free enclosure
for an electronic device, the enclosure containing a coating or adhesive with desiccant
properties. The coating or adhesive comprises a protonated alumina silicate powder
dispersed in a polymer.
[0011] Shores, US-A-5,591,379, discloses a moisture gettering composition for hermetic electronic
devices. The composition is applied as a coating or adhesive to the interior surface
of a device packaging, and the composition comprises a water vapor permeable binder
which has dispersed therein a desiccant, which is preferably a molecular sieve material.
[0012] In none of these patents does Shores teach a multiple device element or a method
to provide moisture-free enclosures for a multiple device element.
[0013] Booe, US-A-4,081,397, describes a composition used for stabilizing the electrical
and electronic properties of electrical and electronic devices. The composition comprises
alkaline earth oxides in an elastomeric matrix. Booe does not teach a multiple device
element or a method used for stabilizing the electrical and electronic properties
of a multiple electrical and electronic device element.
[0014] Inohara and others, US-A-4,357,557, describe a thin-film electroluminescent display
panel sealed by a pair of glass substrates for protection from the environment. The
method includes a protective liquid introduced between the glass substrates, a spacer
positioned for determining the spacing between the pair of substrates, injection holes
formed within one of the substrates to withdraw under vacuum the air and gases from
the cavity defined by the substrates and to introduce the protective liquid into the
cavity, an adhesive adapted to provide bonding between the substrates and the spacer,
a moisture absorptive member introduced into the protective liquid, and an adhesive
to seal the injection hole. Inohara and others do not teach a multiple EL device element
with multiple airtight containers nor a method for fabricating a multiple EL device
element with multiple airtight containers. The handling and sealing problems and solutions
of a multiple EL device element, such as methods to prevent damage to the seal due
to high gas pressure inside the seal region during encapsulation, are not discussed
nor taught by Inohara and others. Although the use of injection holes in one of the
substrates will prevent damage to the seal by permitting excess ambient gas to exit
through the injection holes during encapsulation, Inohara and others do not teach
this purpose for providing the injection holes. Instead the purpose of the injection
holes is to allow introduction of the protective liquid into the cavity defined by
the substrates.
[0015] Taniguchi and others, US-A-5,239,228, describe a method for protecting a thin-film
electroluminescent device similar to Inohara and others with the additional feature
of a groove in the sealing plate to capture excess adhesive. This groove may also
contain a moisture absorption agent. Taniguchi and others also do not teach a multiple
EL device element with multiple airtight containers nor a method for fabricating a
multiple EL device element with multiple airtight containers. The handling and sealing
problems and solutions of a multiple EL device element, such as methods to prevent
damage to the seal due to high gas pressure inside the seal region during encapsulation,
are also not discussed nor taught by Taniguchi and others.
[0016] Harvey, III and others, US-A-5,771,562, describe a method of hermetically sealing
organic light-emitting devices comprising the steps of providing an organic light-emitting
device on a substrate, overcoating the organic light-emitting device with a film of
inorganic dielectric material, and sealingly engaging an inorganic layer over the
dielectric material. Harvey, III and others do not teach a multiple OLED device element
with multiple airtight containers nor a method for fabricating a multiple OLED device
element with multiple airtight containers. Although the inorganic dielectric layer
may provide temporary protection from moisture during the encapsulation process, Harvey,
III and others do not teach how this layer can be used to fabricate a multiple OLED
device element with multiple airtight containers.
[0017] Boroson and others, US-A-6,226,890, describe a method of desiccating an environment
surrounding a highly moisture-sensitive electronic device sealed within an enclosure,
including selecting a desiccant comprised of solid particles having a particle size
range 0.1 to 200 micrometers. The desiccant is selected to provide an equilibrium
minimum humidity level lower than a humidity level to which the device is sensitive
within the sealed enclosure. A binder is chosen that maintains or enhances the moisture
absorption rate of the desiccant for blending the selected desiccant therein. The
binder may be in liquid phase or dissolved in a liquid. A castable blend is formed
including at least the desiccant particles and the binder, the blend having a preferred
weight fraction of the desiccant particles in the blend in a range of 10% to 90%.
The blend is cast in a measured amount onto a portion of an interior surface of an
enclosure to form a desiccant layer thereover, the enclosure having a sealing flange.
The blend is solidified to form a solid desiccant layer, and the electronic device
is sealed with the enclosure along the sealing flange. Boroson and others, however,
do not teach a method of desiccating an environment surrounding a multiple highly
moisture-sensitive electronic device element sealed within multiple enclosures.
[0018] It is the object of the present invention to provide a highly moisture-sensitive
electronic device element having highly moisture-sensitive electronic devices and
a method for fabrication of said element in which damage of the moisture-sensitive
electronic devices within the element due to moisture is prevented and fabrication
of said element is simplified over the present art.
[0019] In one aspect, this object is achieved by a highly moisture-sensitive electronic
device element having highly moisture-sensitive electronic devices comprising:
a) a substrate containing two or more highly moisture-sensitive electronic devices;
b) an encapsulation enclosure encapsulating all of the highly moisture-sensitive electronic
devices on said substrate;
c) sealing material positioned between said substrate and said encapsulation enclosure
to form a complete seal between said substrate and said encapsulation enclosure around
each highly moisture-sensitive electronic device or around groups of highly moisture-sensitive
electronic devices; and
d) wherein the substrate or encapsulation enclosure, or both, contain vent holes and
vent hole seal material.
[0020] In another aspect, this object is achieved by a method of making highly moisture-sensitive
electronic device elements having a plurality of highly moisture-sensitive electronic
devices such as OLED devices on a single substrate wherein the devices are protected
from moisture prior to separating the individual devices from the substrate, comprising
the steps of:
a) providing a vent hole through either the substrate or the encapsulation enclosure,
or both, for each highly moisture-sensitive electronic device or for each group of
highly moisture-sensitive electronic devices on the substrate around which the sealing
material will be placed;
b) placing the sealing material completely around each highly moisture-sensitive electronic
device or around groups of highly moisture-sensitive electronic devices on the substrate
or in positions on the encapsulation enclosure such that after sealing the sealing
material will be positioned completely around each highly moisture-sensitive electronic
device or around groups of highly moisture-sensitive electronic devices;
c) disposing the substrate and the encapsulation enclosure, one of which contains
the sealing material, in close aligned proximity to each other, but spaced apart,
in such aligned proximate position providing an initial ambient pressure;
d) providing relative motion between the substrate and the encapsulation enclosure
until the sealing material contacts both the substrate and the encapsulation enclosure,
the substrate and the encapsulation enclosure are spaced apart within a predetermined
range, and excess ambient gas exits through the vent holes;
e) bonding the sealing material to both the substrate and the encapsulation enclosure;
and
f) sealing the vent holes.
[0021] The elements and methods for fabrication of the elements in accordance with the present
invention of highly moisture-sensitive electronic device elements having highly moisture-sensitive
electronic devices and methods for their fabrication to prevent premature device failure
or premature degradation of device performance provides the following advantages over
prior art methods: reduced handling of devices and encapsulation enclosures by sealing
all of the highly moisture-sensitive devices on a single substrate as a single element
with a single encapsulation enclosure encapsulating all of the highly moisture-sensitive
electronic devices on the substrate prior to separating into smaller single or multiple
device elements; improved protection from moisture prior to exposure to ambient environments;
improved compatibility with automated processes required for high volume manufacturing;
improved compatibility with processing inside a low moisture environment; and reduction
in encapsulation defects due to pressure differentials inside and outside the highly
moisture-sensitive electronic devices.
FIG. 1A shows an unencapsulated highly moisture-sensitive electronic device element
containing multiple highly moisture-sensitive electronic devices on a substrate;
FIG. 1B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section line 1B-1B of FIG. 1A;
FIG. 2A shows a typical multiple LCD element before separation into single LCD devices;
FIG 2B is a schematic sectional view of the multiple LCD element taken along section
line 2B-2B of FIG. 2A;
FIG. 3A shows a typical individually encapsulated multiple OLED element;
FIG. 3B is a schematic sectional view of the multiple OLED element taken along section
line 3B-3B of FIG. 3A;
FIG. 4A shows a highly moisture-sensitive electronic device element comprising a single
encapsulation enclosure and sealing material with damage due to excess pressure;
FIG. 4B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 4B-4B of FIG. 4A;
FIG. 5A shows a highly moisture-sensitive electronic device element comprising a substrate
containing multiple highly moisture-sensitive electronic devices, a single encapsulation
enclosure, and sealing material;
FIG. 5B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 5B-5B of FIG. 5A;
FIG. 6A shows a highly moisture-sensitive electronic device element comprising a substrate
containing multiple highly moisture-sensitive electronic devices, a single encapsulation
enclosure, sealing material, water absorbing material, and a temporary moisture protection
layer;
FIG. 6B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 6B-6B of FIG. 6A;
FIG. 7A shows a highly moisture-sensitive electronic device element comprising a substrate
containing multiple highly moisture-sensitive electronic devices, sealing material
with no gaps, and a vent hole through the substrate for each moisture-sensitive electronic
device in close aligned proximity to, but spaced apart from, an encapsulation enclosure;
FIG. 7B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 7B,C,D-7B,C,D of FIG. 7A;
FIG. 7C is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 7B,C,D-7B,C,D of FIG. 7A after relative motion
of the substrate and the encapsulation enclosure to a predetermined spacing;
FIG. 7D is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 7B,C,D-7B,C,D of FIG. 7A after sealing the
vent holes;
FIG. 8A shows a highly moisture-sensitive electronic device element comprising a substrate
containing multiple highly moisture-sensitive electronic devices and sealing material
with gaps in close aligned proximity to, but spaced apart from, an encapsulation enclosure;
FIG. 8B is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 8B,C of FIG. 8A;
FIG. 8C is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 8B,C of FIG. 8A after relative motion of
the substrate and the encapsulation enclosure to the point where the sealing material
contacts both the substrate and the encapsulation enclosure;
FIG. 8D shows a highly moisture-sensitive electronic device element comprising a substrate
containing multiple highly moisture-sensitive electronic devices, sealing material,
and an encapsulation enclosure after relative motion of the substrate and the encapsulation
enclosure to a predetermined spacing fills in the gaps by spreading of the sealing
material;
FIG. 8E is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 8E-8E of FIG. 8D.
[0022] The term "highly moisture-sensitive electronic device element" is employed to designate
an element that contains one or more highly moisture-sensitive electronic devices
during or after fabrication, or both, during and after fabrication of the highly moisture-sensitive
electronic devices is complete. The term "highly moisture-sensitive electronic device"
is employed to designate any electronic device that is susceptible to a measurable
degradation of device performance at ambient moisture levels greater than 1000 ppm.
The term "substrate" is employed to designate organic, inorganic, or combination organic
and inorganic solids on which one or more highly moisture-sensitive electronic devices
are fabricated. The term "encapsulation enclosure" is employed to designate organic,
inorganic, or combination organic and inorganic solids used to protect one or more
highly moisture-sensitive electronic devices from moisture by preventing or limiting
moisture permeation through the encapsulation enclosures. The term "sealing material"
is employed to designate organic, inorganic, or combination organic and inorganic
materials used to bond encapsulation enclosures to substrates and to protect one or
more highly moisture-sensitive electronic devices from moisture by preventing or limiting
moisture permeation through the sealing materials. The term "gap" is employed to designate
a discontinuity in the sealing material surrounding one or more electronic devices.
The term "water absorbing material" is employed to designate inorganic materials used
to physically or chemically absorb or react with moisture that would otherwise damage
the highly moisture-sensitive electronic devices. The term "temporary moisture protection
layer" is employed to designate organic, inorganic, or combination organic and inorganic
materials used to prevent or limit moisture induced damage to the highly moisture-sensitive
electronic devices during short term exposure to ambient moisture levels greater than
1000 ppm, where short term is typically less than 10 days.
[0023] Referring now to FIG. 5A there is shown one embodiment of the highly moisture-sensitive
electronic device element 14 in accordance with the present invention. A highly moisture-sensitive
electronic device element 14 is shown comprising a substrate 10 containing multiple
highly moisture-sensitive electronic devices 12, a single encapsulation enclosure
30 encapsulating all of the highly moisture-sensitive electronic devices 12 on the
substrate 10, and sealing material 20 surrounding each highly moisture-sensitive electronic
device 12 with no gaps in the sealing material 20. FIG. 5B is a schematic sectional
view of the highly moisture-sensitive electronic device element 14 taken along section
lines 5B-5B of FIG. 5A. In FIG. 5A and FIG. 5B the highly moisture-sensitive electronic
device element 14 is shown comprising four highly moisture-sensitive electronic devices
12, but the highly moisture-sensitive electronic device element of this invention
may comprise any number of highly moisture-sensitive electronic devices greater than
one. By encapsulating all of the highly moisture-sensitive electronic devices on the
substrate with a single encapsulation enclosure, the advantage of reduced handling
over the prior art of separately encapsulating each highly moisture-sensitive electronic
device on the substrate with separate encapsulation enclosures is achieved. The substrate
10 and the encapsulation enclosure 30 shown in FIG. 5A and FIG. 5B may be an organic
solid, an inorganic solid, or a combination of organic and inorganic solids. The substrate
and the encapsulation enclosure may be rigid or flexible and may be processed as separate
individual pieces, such as sheets or wafers, or as a continuous roll. Typical substrate
and encapsulation enclosure materials include glass, plastic, metal, ceramic, semiconductor,
metal oxide, metal nitride, metal sulfide, semiconductor oxide, semiconductor nitride,
semiconductor sulfide, carbon, or combinations thereof. The substrate and the encapsulation
enclosure may be a homogeneous mixture of materials, a composite of materials, or
multiple layers of materials. The substrate, the encapsulation enclosure, or both,
contain vent holes 100 and vent hole seal material 102. The vent hole seal material
can be the same material as the sealing material used to bond the substrate and the
encapsulation enclosure or may be a different enclosing material. The vent hole enclosing
material may be organic, inorganic, or a combination thereof. Examples of enclosing
materials are adhesives, solders, tapes, multilayer laminates bonded with adhesive,
and inorganic covers bonded with adhesive. The sealing material 20 shown in FIG. 5A
and FIG. 5B surrounds each individual highly moisture-sensitive electronic device,
but the sealing material could also surround groups of two or more highly moisture-sensitive
electronic devices if the final product required more than one highly moisture-sensitive
electronic device within a single element. In addition, the sealing material surrounding
each highly moisture-sensitive electronic device or groups of highly moisture-sensitive
electronic devices contains no gaps such that the highly moisture-sensitive electronic
device element is protected from moisture prior to separating into smaller single
or multiple device elements. The sealing material may be organic, inorganic, or a
combination of organic and inorganic. The sealing material may be bonded to the substrate
and the encapsulation enclosure by melting and cooling or by reaction curing. Typical
materials bonded by melting and cooling include glass; hot melt adhesives such as
polyolefins, polyesters, polyamides, or combinations thereof; or inorganic solders
such as indium, tin, lead, silver, gold, or combinations thereof. Typical reaction
curing methods include reactions resulting from heat, radiation such as UV radiation,
mixing of two or more components, exposure to ambient moisture, removal of ambient
oxygen, or combinations thereof. Typical materials bonded by reaction curing include
acrylates, epoxies, polyurethanes, silicones, or combinations thereof. Other inorganic
material typically used in sealing materials include glass, ceramic, metal, semiconductor,
metal oxide, semiconductor oxide, or combinations thereof.
[0024] Referring now to FIG. 6A there is shown another embodiment of the highly moisture-sensitive
electronic device element 14 in accordance with the present invention. A highly moisture-sensitive
electronic device element 14 is shown comprising a substrate 10 containing multiple
highly moisture-sensitive electronic devices 12, a single encapsulation enclosure
30 encapsulating all of the highly moisture-sensitive electronic devices 12 on the
substrate 10, sealing material 20 defining a space surrounding each highly moisture-sensitive
electronic device 12 with no gaps in the sealing material 20, water absorbing material
60 positioned between the substrate 10 and the encapsulation enclosure 30 and within
the space defined by the sealing material 20, and temporary moisture protection layers
62 coated over each of the highly moisture-sensitive electronic devices 12. FIG. 6B
is a schematic sectional view of the highly moisture-sensitive electronic device element
14 taken along section lines 6B-6B of FIG. 6A. Details of the highly moisture-sensitive
electronic devices 12, substrate 10, encapsulation enclosure 30, and sealing material
20 are identical with the embodiment shown in FIG. 5A and FIG. 5B. Also as in the
embodiment shown in FIG. 5A and FIG. 5B, the substrate, the encapsulation enclosure,
or both, contain vent holes 100 and vent hole seal material 102. Details of the vent
hole seal material are identical with the embodiment shown in FIG. 5A and FIG. 5B.
The water absorbing material is used to physically or chemically absorb or react with
moisture that would otherwise damage the highly moisture-sensitive electronic devices.
Typical water absorbing materials include alkaline metal oxides, alkaline earth metal
oxides, sulfates, metal halides, perchlorates, molecular sieves, and metals with work
functions less than 4.5 eV and capable of being oxidized in the presence of moisture,
or combinations thereof. Water absorbing material may be packaged within moisture
permeable containers or binders. The water absorbing material may be a single material,
a homogeneous mixture of materials, a composite of materials, or multiple layers of
materials. Temporary moisture protection layers are used to prevent or limit moisture
induced damage to the highly moisture-sensitive electronic devices during short term
exposure to ambient moisture levels greater than 1000 ppm. The temporary moisture
protection layer is organic material, inorganic material, or a combination thereof.
Typical organic materials include epoxies, polyurethanes, polyureas, acrylates, silicones,
polyamides, polyimides, phenolics, polyvinyls, phenoxies, polysulfones, polyolefins,
polyesters, or combinations thereof. Typical inorganic materials include glass, ceramic,
metal, semiconductor, metal oxide, metal nitride, metal sulfide, semiconductor oxide,
semiconductor nitride, semiconductor sulfide, carbon, or combinations thereof. The
temporary moisture protection layer may be a single material, a homogeneous mixture
of materials, a composite of materials, or multiple layers of materials.
[0025] Referring now to FIGS. 7A to 7D there is shown an embodiment of the method of making
highly moisture-sensitive electronic device elements having a plurality of highly
moisture-sensitive electronic devices such as OLED devices on a single substrate wherein
the devices are protected from moisture prior to separating the individual devices
from the substrate in accordance with the present invention. FIG. 7A shows a highly
moisture-sensitive electronic device element 14 comprising a substrate 10 containing
multiple highly moisture-sensitive electronic devices 12, sealing material 20 surrounding
each highly moisture-sensitive electronic device 12 with no gaps in the sealing material
20, and a vent hole 100 through the substrate for each highly moisture-sensitive electronic
device 12 in close aligned proximity to, but spaced apart from, an encapsulation enclosure
30 encapsulating all of the highly moisture-sensitive electronic devices 12 on the
substrate 10. FIG. 7B is a schematic sectional view of the highly moisture-sensitive
electronic device element 14 taken along section lines 7B,C,D-7B,C,D of FIG. 7A. The
ambient pressure may be above, below, or equal to atmospheric pressure. Details of
the highly moisture-sensitive electronic devices 12, substrate 10, encapsulation enclosure
30, and sealing material 20 are identical with the embodiment shown in FIG. 5A and
5B. In other embodiments the water absorbing material 60, temporary moisture protection
layer 62 ,or both, described in detail in the embodiment shown in FIG. 6A and 6B,
may be coated on the highly moisture-sensitive electronic devices 12 or on the encapsulation
enclosure. In another embodiment the vent holes may be through the encapsulation enclosure
or through both the substrate and the encapsulation enclosure. FIG. 7C is a schematic
sectional view of the highly moisture-sensitive electronic device element 14 taken
along section lines 7B,C,D-7B,C,D of FIG. 7A after relative motion 90 of the substrate
10 and the encapsulation enclosure 30 to the point where the substrate 10 and the
encapsulation enclosure 30 are spaced apart within a predetermined range, excess ambient
gas has exited through the vent holes 100, and the sealing material 20 has been bonded
to both the substrate 10 and the encapsulation enclosure 30. Because excess gas may
exit through the vent holes, the ambient surrounding the substrate 10, the encapsulation
enclosure 30, and the sealing material 20 is equal to the pressure within spaces defined
between the substrate 10, the encapsulation enclosure 30, and the sealing material
20, thereby preventing deformation of the sealing material 20. Bonding the sealing
material 20 to both the substrate 10 and the encapsulation enclosure 30 may be accomplished
by melting and cooling, reaction curing, or a combination thereof. The reaction curing
may include reactions resulting from heat, radiation, mixing of two or more components,
exposure to ambient moisture, removal of ambient oxygen, or combinations thereof.
FIG. 7D is a schematic sectional view of the highly moisture-sensitive electronic
device element taken along section lines 7B,C,D-7B,C,D of FIG. 7A after sealing the
vent holes with vent hole seal material. In another embodiment the vent holes may
be sealed before or during bonding of the sealing material to the substrate and the
encapsulation body. Details of the vent hole seal material are identical with the
embodiment shown in FIG. 5A and FIG. 5B. After completing the method described in
FIG. 7A to 7D, the highly moisture-sensitive electronic devices are typically separated
into individual devices or groups of devices having a portion of the initial substrate.
[0026] Referring now to FIGS. 8A to 8E there is shown another embodiment of the method of
making highly moisture-sensitive electronic device elements having a plurality of
highly moisture-sensitive electronic devices such as OLED devices on a single substrate
wherein the devices are protected from moisture prior to separating the individual
devices from the substrate in accordance with the present invention. FIG. 8A shows
a highly moisture-sensitive electronic device element 14 comprising a substrate 10
containing multiple highly moisture-sensitive electronic devices 12 and sealing material
20 surrounding each highly moisture-sensitive electronic device 12 with gaps in the
sealing material 20 in close aligned proximity to, but spaced apart from, an encapsulation
enclosure 30 encapsulating all of the highly moisture-sensitive electronic devices
12 on the substrate 10. FIG. 8B is a schematic sectional view of the highly moisture-sensitive
electronic device element 14 taken along section lines 8B,C-8B,C of FIG. 8A. The ambient
pressure may be above, below, or equal to atmospheric pressure. Details of the highly
moisture-sensitive electronic devices 12, substrate 10, encapsulation enclosure 30,
and sealing material 20 are identical with the embodiment shown in FIG. 5A and 5B.
In other embodiments the water absorbing material 60, temporary moisture protection
layer 62, or both, described in detail in the embodiment shown in FIG. 6A and 6B may
be coated on the highly moisture-sensitive electronic devices 12 or on the encapsulation
enclosure.
[0027] FIG. 8C is a schematic sectional view of the highly moisture-sensitive electronic
device element 14 taken along section lines 8B,C-8B,C of FIG. 8A after relative motion
90 of the substrate 10 and the encapsulation enclosure 30 to the point where the sealing
material 20 contacts both the substrate 10 and the encapsulation enclosure 30. FIG.
8D shows a highly moisture-sensitive electronic device element 14 after relative motion
between the substrate 10 and the encapsulation enclosure 30 to a predetermined spacing
range, during which excess ambient gas escapes through the gaps until the gaps are
filled by spreading the sealing material, and after the sealing material 20 has been
bonded to both the substrate 10 and the encapsulation enclosure 30. FIG. 8E is a schematic
sectional view of the highly moisture-sensitive electronic device element taken along
section lines 8E-8E of FIG. 8D. In this embodiment the gap size is selected such that
the gap will fill in by spreading of the sealing material during the step where the
substrate and the encapsulation enclosure are moved to their final predetermined spacing
range. Because excess gas may exit through the gap, the pressure difference within
spaces defined between the substrate 10, the encapsulation enclosure 30, and the sealing
material 20 relative to the ambient pressure is reduced to thereby prevent deformation
of the sealing material 20. Bonding the sealing material 20 to both the substrate
10 and the encapsulation enclosure 30 may be accomplished by the same methods described
in the embodiment of FIG. 7A to 7D. After completing the method described in FIG.
8A to 8E, the highly moisture-sensitive electronic devices are typically separated
into individual devices or groups of devices having a portion of the initial substrate.
Example
I. Construction of the test structure
[0028] A plurality of identical test structures were fabricated by the following process
sequence:
(1) glass substrates representing substrates containing multiple highly moisture-sensitive
electronic devices were cleaned by ultrasonicating in acetone and isopropyl alcohol
and rinsing in deionized water;
(2) glass encapsulation enclosures with or without vent holes and containing multiple
cavities formed by selectively etching the glass substrate were cleaned, prior to
forming a water absorbing layer, by a cleaning process identical to the substrate
cleaning process described in step (1) above;
(3) water absorbing layers were formed and cured within the cavities of the encapsulation
enclosures;
(4) sealing material was placed completely around each cavity or each vent hole and
cavity on the encapsulation enclosure;
(5) the substrate and the encapsulation enclosure containing the sealing material
were placed in close aligned proximity to each other, but spaced apart at atmospheric
pressure;
(6) relative motion between the substrate and the encapsulation enclosure was provided
until the sealing material contacted both the substrate and the encapsulation enclosure
and the substrate and the encapsulation enclosure were spaced apart by 20-30 micrometers;
(7) the sealing material was bonding to both the substrate and the encapsulation enclosure
to form the test structure; and
(8) the vent holes, if present, were sealed with enclosing material.
II. Results
[0029] The quality of the encapsulation for all locations within the test structure was
judged based on the quality of the sealing material after bonding. If damage was evident
to the seal material due to pressure differences inside and outside the sealing material,
the encapsulation quality was rated as poor. If no damage was evident, the encapsulation
quality was rated as good. If slight damage was evident, the encapsulation quality
was rated as fair. The test structures with vent holes all had encapsulation quality
rated as good. The control test structures without vent holes all had encapsulation
quality rated as poor.
[0030] Other features of the invention are included below.
[0031] The highly moisture-sensitive electronic device element wherein the substrate includes
rigid or flexible: glass, plastic, metal, ceramic, semiconductor, metal oxide, metal
nitride, metal sulfide, semiconductor oxide, semiconductor nitride, semiconductor
sulfide, carbon, or combinations thereof.
[0032] The highly moisture-sensitive electronic device element wherein the encapsulation
enclosure includes rigid or flexible: glass, plastic, metal, ceramic, semiconductor,
metal oxide, metal nitride, metal sulfide, semiconductor oxide, semiconductor nitride,
semiconductor sulfide, carbon, or combinations thereof.
[0033] The highly moisture-sensitive electronic device element wherein the sealing material
is organic material, inorganic material, or combinations thereof that is melted and
cooled or reaction cured.
[0034] The highly moisture-sensitive electronic device element wherein reaction curing includes
reactions resulting from heat, radiation, mixing of two or more components, exposure
to ambient moisture, removal of ambient oxygen, or combinations thereof.
[0035] The highly moisture-sensitive electronic device element wherein the organic material
is selected from the group consisting of epoxies, polyurethanes, acrylates, silicones,
polyamides, polyolefins, and polyesters, or combinations thereof.
[0036] The highly moisture-sensitive electronic device element wherein the inorganic material
is selected from the group consisting of glass, ceramic, metal, semiconductor, metal
oxide, semiconductor oxide, and metal solder, or combinations thereof.
[0037] The highly moisture-sensitive electronic device element wherein the water absorbing
material is selected from the group consisting of alkaline metal oxides, alkaline
earth metal oxides, sulfates, metal halides, perchlorates, molecular sieves, and metals
with work functions less than 4.5 eV and capable of being oxidized in the presence
of moisture, or combinations thereof.
[0038] The highly moisture-sensitive electronic device element wherein the sealing material
or other enclosing material is used to seal the vent holes.
[0039] The highly moisture-sensitive electronic device element wherein the enclosing material
is organic, inorganic, or a combination thereof.
[0040] A highly moisture-sensitive electronic device element having highly moisture-sensitive
electronic devices comprising:
a) a substrate containing two or more moisture-sensitive electronic devices that have
been coated with a temporary moisture protection layer;
b) an encapsulation enclosure encapsulating all of the highly moisture-sensitive electronic
devices on said substrate;
c) sealing material positioned between said substrate and said encapsulation enclosure
to form a complete seal between said substrate and said encapsulation enclosure around
each moisture-sensitive electronic device or around groups of moisture-sensitive electronic
devices; and
d) wherein the substrate or encapsulation enclosure, or both, contain vent holes and
vent hole seal material.
[0041] The highly moisture-sensitive electronic device element wherein the substrate includes
rigid or flexible: glass, plastic, metal, ceramic, semiconductor, metal oxide, metal
nitride, metal sulfide, semiconductor oxide, semiconductor nitride, semiconductor
sulfide, carbon, or combinations thereof.
[0042] The highly moisture-sensitive electronic device element wherein the encapsulation
enclosure includes rigid or flexible: glass, plastic, metal, ceramic, semiconductor,
metal oxide, metal nitride, metal sulfide, semiconductor oxide, semiconductor nitride,
semiconductor sulfide, carbon, or combinations thereof.
[0043] The highly moisture-sensitive electronic device element wherein the sealing material
is organic material, inorganic material, or combinations thereof that is melted and
cooled or reaction cured.
[0044] The highly moisture-sensitive electronic device element wherein reaction curing includes
reactions resulting from heat, radiation, mixing of two or more components, exposure
to ambient moisture, removal of ambient oxygen, or combinations thereof.
[0045] The highly moisture-sensitive electronic device element wherein the organic material
is selected from the group consisting of epoxies, polyurethanes, acrylates, silicones,
polyamides, polyolefins, and polyesters, or combinations thereof.
[0046] The highly moisture-sensitive electronic device element wherein the inorganic material
is selected from the group consisting of glass, ceramic, metal, semiconductor, metal
oxide, semiconductor oxide, and metal solder, or combinations thereof.
[0047] The highly moisture-sensitive electronic device element wherein the temporary moisture
protection layer is organic material, inorganic material, or a combination thereof.
[0048] The highly moisture-sensitive electronic device element wherein the organic material
is selected from the group consisting of epoxies, polyurethanes, polyureas, acrylates,
silicones, polyamides, polyimides, phenolics, polyvinyls, phenoxies, polysulfones,
polyolefins, and polyesters, or combinations thereof.
[0049] The highly moisture-sensitive electronic device element wherein the inorganic material
is selected from the group consisting of glass, ceramic, metal, semiconductor, metal
oxide, metal nitride, metal sulfide, semiconductor oxide, semiconductor nitride, semiconductor
sulfide, and carbon, or combinations thereof.
[0050] The highly moisture-sensitive electronic device element wherein the sealing material
or other enclosing material is used to seal the vent holes.
[0051] The highly moisture-sensitive electronic device element wherein the enclosing material
is organic, inorganic, or a combination thereof.
[0052] A method of making highly moisture-sensitive electronic device elements having a
plurality of highly moisture-sensitive electronic devices such as OLED devices on
a single substrate wherein the devices are protected from moisture prior to separating
the individual devices from the substrate, comprising the steps of:
a) providing a vent hole through either the substrate or the encapsulation enclosure,
or both, for each highly moisture-sensitive electronic device or for each group of
highly moisture-sensitive electronic devices on the substrate around which the sealing
material will be placed;
b) placing the sealing material completely around each highly moisture-sensitive electronic
device or around groups of highly moisture-sensitive electronic devices on the substrate
or in positions on the encapsulation enclosure such that after sealing the sealing
material will be positioned completely around each highly moisture-sensitive electronic
device or around groups of highly moisture-sensitive electronic devices;
c) disposing the substrate and the encapsulation enclosure, one of which contains
the sealing material, in close aligned proximity to each other, but spaced apart,
in such aligned proximate position providing an initial ambient pressure;
d) providing relative motion between the substrate and the encapsulation enclosure
until the sealing material contacts both the substrate and the encapsulation enclosure,
the substrate and the encapsulation enclosure are spaced apart within a predetermined
range, and excess ambient gas exits through the vent holes;
e) bonding the sealing material to both the substrate and the encapsulation enclosure;
and
f) sealing the vent holes.
[0053] The method wherein the sealing material or other enclosing material is used to seal
the vent holes.
[0054] The method wherein the enclosing material is organic, inorganic, or a combination
thereof.
[0055] The method wherein the bonding step is accomplished by melting and cooling, reaction
curing, or a combination thereof.
[0056] The method wherein the reaction includes reactions resulting from heat, radiation,
mixing of two or more components, exposure to ambient moisture, removal of ambient
oxygen, or combinations thereof.
[0057] The method wherein the substrate includes rigid or flexible: glass, plastic, metal,
ceramic, semiconductor, metal oxide, metal nitride, metal sulfide, semiconductor oxide,
semiconductor nitride, semiconductor sulfide, carbon, or combinations thereof.
[0058] The method wherein the encapsulation enclosure includes rigid or flexible: glass,
plastic, metal, ceramic, semiconductor, metal oxide, metal nitride, metal sulfide,
semiconductor oxide, semiconductor nitride, semiconductor sulfide, carbon, or combinations
thereof.
[0059] The method wherein the sealing material is organic material, inorganic material,
or combinations thereof.
[0060] The method wherein the organic material is selected from the group consisting of
epoxies, polyurethanes, acrylates, silicones, polyamides, polyolefins, and polyesters,
or combinations thereof.
[0061] The method wherein the inorganic material is selected from the group consisting of
glass, ceramic, metal, semiconductor, metal oxide, semiconductor oxide, and metal
solder, or combinations thereof.
[0062] The method further including the step of separating the highly moisture-sensitive
electronic devices into individual devices or groups of devices having a portion of
the initial substrate.
[0063] The method further including the step of coating a substrate containing two or more
highly moisture-sensitive electronic devices with a temporary moisture protection
layer; or coating a water absorbing material onto either the substrate or an encapsulation
enclosure in positions on the substrate or on the encapsulation enclosure such that
after bonding, the water absorbing material will be positioned within each highly
moisture-sensitive electronic device or within each group of highly moisture-sensitive
electronic devices; or coating both said temporary moisture protection layer and said
water absorbing material.
[0064] The method wherein the water absorbing material is selected from the group consisting
of alkaline metal oxides, alkaline earth metal oxides, sulfates, metal halides, perchlorates,
molecularsieves, and metals with work functions less than 4.5 eV and capable of being
oxidized in the presence of moisture, or combinations thereof.
[0065] The method wherein the temporary moisture protection layer is organic material, inorganic
material, or a combination thereof.
[0066] The method wherein the organic material is selected from the group consisting of
epoxies, polyurethanes, polyureas, acrylates, silicones, polyamides, polyimides, phenolics,
polyvinyls, phenoxies, polysulfones, polyolefins, and polyesters, or combinations
thereof.
[0067] The method wherein the inorganic material is selected from the group consisting of
glass, ceramic, metal, semiconductor, metal oxide, metal nitride, metal sulfide, semiconductor
oxide, semiconductor nitride, semiconductor sulfide, and carbon, or combinations thereof.
[0068] A method of making highly moisture-sensitive electronic device elements having a
plurality of highly moisture-sensitive electronic devices such as OLED devices on
a single substrate wherein the devices are protected from moisture prior to separating
the individual devices from the substrate, comprising the steps of:
a) placing the sealing material around each highly moisture-sensitive electronic device
or around groups of highly moisture-sensitive electronic devices on the substrate
or in positions on the encapsulation enclosure leaving one or more positions wherein
there is a gap not covered by sealing material;
b) disposing the substrate and the encapsulation enclosure, one of which contains
the sealing material, in close aligned proximity to each other, but spaced apart,
in such aligned proximate position providing an initial ambient pressure;
c) providing relative motion between the substrate and the encapsulation enclosure
until the sealing material contacts both the substrate and the encapsulation enclosure,
the substrate and the encapsulation enclosure are spaced apart within a predetermined
range, and excess ambient gas exits through the gaps until the gaps are filled in
by spreading the sealing material; and
d) bonding the sealing material to both the substrate and the encapsulation enclosure.
[0069] The method wherein the bonding step is accomplished by melting and cooling, reaction
curing, or a combination thereof.
[0070] The method wherein the reaction includes reactions resulting from heat, radiation,
mixing of two or more components, exposure to ambient moisture, removal of ambient
oxygen, or combinations thereof.
[0071] The method wherein the substrate includes rigid or flexible: glass, plastic, metal,
ceramic, semiconductor, metal oxide, metal nitride, metal sulfide, semiconductor oxide,
semiconductor nitride, semiconductor sulfide, carbon, or combinations thereof.
[0072] The method wherein the encapsulation enclosure includes rigid or flexible: glass,
plastic, metal, ceramic, semiconductor, metal oxide, metal nitride, metal sulfide,
semiconductor oxide, semiconductor nitride, semiconductor sulfide, carbon, or combinations
thereof.
[0073] The method wherein the sealing material is organic material, inorganic material,
or combinations thereof.
[0074] The method wherein the organic material is selected from the group consisting of
epoxies, polyurethanes, acrylates, silicones, polyamides, polyolefins, and polyesters,
or combinations thereof.
[0075] The method wherein the inorganic material is selected from the group consisting of
glass, ceramic, metal, semiconductor, metal oxide, semiconductor oxide, and metal
solder, or combinations thereof.
[0076] The method further including the step of separating the highly moisture-sensitive
electronic devices into individual devices or groups of devices having a portion of
the initial substrate.
[0077] The method further including the step of coating a substrate containing two or more
highly moisture-sensitive electronic devices with a temporary moisture protection
layer; or coating a water absorbing material onto either the substrate or an encapsulation
enclosure in positions on the substrate or on the encapsulation enclosure such that
after bonding, the water absorbing material will be positioned within each highly
moisture-sensitive electronic device or within each group of highly moisture-sensitive
electronic devices; or coating both said temporary moisture protection layer and said
water absorbing material.
[0078] The method wherein the water absorbing material is selected from the group consisting
of alkaline metal oxides, alkaline earth metal oxides, sulfates, metal halides, perchlorates,
molecular sieves, and metals with work functions less than 4.5 eV and capable of being
oxidized in the presence of moisture, or combinations thereof.
[0079] The method wherein the temporary moisture protection layer is organic material, inorganic
material, or a combination thereof.
[0080] The method wherein the organic material is selected from the group consisting of
epoxies, polyurethanes, polyureas, acrylates, silicones, polyamides, polyimides, phenolics,
polyvinyls, phenoxies, polysulfones, polyolefins, and polyesters, or combinations
thereof.
[0081] The method wherein the inorganic material is selected from the group consisting of
glass, ceramic, metal, semiconductor, metal oxide, metal nitride, metal sulfide, semiconductor
oxide, semiconductor nitride, semiconductor sulfide, and carbon, or combinations thereof.